EXPERIMENTAL WORK WITH RAW ROCK PHOSPHATE. 



51 



In 1889, however, the North Louisiana Experiment Station, at 

 Calhoun, La.,^ began a five-year experiment to test the effect of vari- 

 ous phosphatic fertilizers (alone and in combination with other ma- 

 terials) on cotton. The results were published year by year, but 

 in no bulletin is there a table giving the complete results for all five 

 years. They have been consolidated by the authors in Table XXVI. 



Neither the size of the plots nor the character of the soil used in 

 this experiment are mentioned, but the soil at the station is said to 

 be on the whole sandy. The field was plowed during the winter 

 of each year, the fertilizer drilled in in the spring, and the seed 

 planted shortly afterwards. The crop was cultivated and hoed sev- 

 eral times during each growing season. 



The climatic conditions during the third and fifth years are not 

 described, but during 1889, and in July and August of 1890, droughts 

 somewhat handicapped the crops. In 1892 late planting and ex- 

 cessive rains seriously affected the yields for that year. 



Table XXVI. — Results obtained in the groiuing of cotton on plot No. 2 

 (Calhoun, La.) (1889-1893). 



Fertilizer. 



Applica- 

 tion per 

 acre. 



Yield per acre of seed cotton. 



1892 



1893 



Gypsum ^ 



Dissolved bone black. 



Basal mixture i 



Basal mixture i 



Dissolved bone black . 



Gypsum 



Acid phosphate . 

 Basal mixture i . 



No manure 



Basal mixture i . 



Acid phosphate . 



Bone meal 



Basal mixture i. 

 Basal mixture i . 



Bone meal 



Floats 



Basal mixture i . 

 Basal mixture i . 



Floats 



No manure 



Pounds. 

 80 

 160 

 600 

 600 

 ' 160 



1 320 



80 

 160 

 600 



600 

 160 

 320 

 160 

 600 

 600 

 160 

 320 

 160 

 600 

 600 

 160 

 320 



Pounds. 



.. 1,520 



1,630 



1,970 



• 2 1,990 



1,390 

 1,350 

 1,720 

 1,010 



2 1,950 



770 

 1,170 



2 1, 305 



920 



2 835 

 330 



Pounds. 

 1,810 

 1,770 

 1,800 



2 2, 133 



1,620 



1,680 

 1,870 

 1,210 



2 1, 760 



1,180 

 1,370 



2 1, 335 



690 

 1,100 



2 1,015 



630 



Pounds. 

 1,860 

 1,870 

 1,780 



2 2, 215 



1,710 

 1,620 

 1,700 

 1,380 



2 1,735 



1,330 

 1,480 



* 1, 545 



1,030 

 1,190 



2 1, 255 



730 



Pounds. 

 730 

 820 

 710 



2920 



760 

 780 

 920 

 520 



590 

 660 



2700 



460 

 560 



2 680 

 380 



Pounds. 

 1,250 

 1,240 

 1,540 



2 1,645 



1,320 



1,160 



1,450 



960 



2 1,285 



1,170 



21,130 



610 

 1,100 



1 Basal mixture = 480 pounds cotton-seed meal and 200 pounds kainit. 



2 Average of two plots. 



It is apparent that the plots of this experimental field were far 

 from uniform. Moreover, small applications of raw rock phosphate 

 (160 pounds per acre) used on continual cotton without incorporat- 

 ing more organic matter in the soil than was supplied in the basal 

 mixture employed in this experiment could hardly be expected to 

 produce marked effects on the crop yield. 



iLa. Agr. Expt. Sta., Bui. No. 27 (1889) (old series). Buls. Nos. 8 (1891) ; 16 (1892) ; 

 26, 29 (1894) (new series). 



